Update VE core submodule to master (71f0151)

New changes:
0413871 Merge b/strong and i/em annotations
9b6c247 Look for comparable annotations when toggling
3114e8c Add debug bars to surface widgets
b8733dc Prevent SurfaceWidgets from focussing themselves
e5829ec Localisation updates from https://translatewiki.net.
71f0151 Update OOjs UI to v0.1.0-pre (497baca586)

Change-Id: Id3dda20b83e4871c12e3795e9204fe6137f11d5a